The present invention relates to a rigid rapid-connection device of the detachable and self-aligning type and, in particular, a device comprising at least one main body endowed with a seat and at least one supported element endowed with a shank fit to be received into the seat of the main body.
Similar connection devices are known for instance for use in modular tooling assemblies destined for the machine-tools such as modular tool-carrier systems.
Independently of whether the tool is of the rotating or fixed type, the essential requirements of all these systems are precision in mounting the tool, repeatability of positioning the tool when the tool is again positioned on the machine after having been taken off the same, as well as stability of the axial and radial locking. Such modular tooling systems must also guarantee high rapidity in mounting and dismounting the tool.
An example of a similar device is described in the European Patent nr. EP-0548878 which relates to a device for connecting two cylindrical components in a precise way, the first of which, for instance a tool or an adapter, has an expandable transverse stem associated with it. The component to which the expandable stem is associated is inserted into a seat of a second component, for instance a basic holder, with the stem in retracted condition, until the same stem is brought into correspondence with at least one through hole to allow the stem to be extended. Once this position is reached, the stem is expanded to lock conical surface portions of the heads of the stem into corresponding recesses, also conical, in the second component.
One of the disadvantages of a similar system consists in necessarily requiring that each tool and each adapter be equipped with the expanding stem. Noting that the locking of the tool or adapter is effected by engaging the heads of the stem in corresponding recesses of the basic holder, all these elements necessarily require extremely accurate machining to assure precise positioning of the tool. Consequently, providing each tool and each adapter with an expanding stem is extremely expensive.
Another example, always related to the modular tooling systems, is described in European Patent nr. EP-0547049 which relates to a device for connecting two sections of a tool having a common axis. In this case, the shank of a tool or an adapter is endowed with a pin that has one extremity with a conical projection and the other extremity with a conical cavity. The basic holder into whose seat the shank is inserted is instead endowed with screws that have extremities respectively complementary to those of the pin. The locking of the screws causes the deformation of the seat of the basic holder.
This particular locking characteristic could result in not being very precise and could give rise to errors of positioning and to possible unbalancing of the system, a not inconsiderable drawback above all for the tools that rotate at high speed. This system offers a limited contact surface between shank and seat thus in fact limiting the maximum transmissible torque. Furthermore, the deformation of the seal of the basic holder can, over time, jeopordise the operation of the same basic holder.
In any case, these devices of known type are not in any way equipped with means to ensure the necessary safety of manipulation of the interconnected members and of the locking devices, in particular for the tools that, once the locking member has been loosened, could become detached from the basic holder and fall provoking damage or injury, above all in the case in which the tools are suspended and oriented with their extremity facing downward.
The object of the present invention is to propose a detachable connection device of the self-aligning type that ensures high precision of mutual positioning of the two elements interconnected without requiring particularly precise machining of the components and of the locking means.
Another object of the present invention is to propose a connection device of the detachable type that ensures high strength locking between two mutually connected elements.
A further object of the present invention is to propose a self-aligning connection device that is particularly rapid to operate both during the phase of connection of the two elements and during the phase of separation of the same.
Yet another object of the present invention is to propose a self-aligning connection device that offers high safety of manipulation of the mutually connected elements and of the locking devices.
According to the present invention, these objects are achieved by a rigid detachable connection device of a self-aligning type, comprising at least one main body endowed with a seat and at least one supported element endowed with a shank fit to be received into the seat of the main body, characterised by comprising means for elastically deforming the shank and for bringing at least two external surfaces of the same into close contact with the inside surface of the seat.
The uniform and symmetrical deformation of the shank of the supported element inside the seat of the main body guarantees above all high strength locking, maintaining simultaneously high precision of positioning without necessarily requiring machining within particularly narrow tolerances.
The shank and its respective seat are preferably cylindrical in shape and the means for elastically deforming the shank comprise in particular at least one actuator member which extends and contracts in length along a direction transverse to the axis of the shank and seat. The shank comprises in particular at least two opposed portions separated by a pair of transverse through holes with axes parallel to the direction of extension and of contraction of the actuator member and by a pair of corresponding slits connecting the respective holes to form an open slot which allows the passage between them of the actuator member during the insertion of the shank into the seat of the main body while the actuator member is in a first pre-set position. The two portions of the shank guarantee a large surface of contact with the inside surface of the seat in the main body.
The actuator member is arranged in the main body with the possibility of rotation about an axis parallel to the extension/contraction direction of the same actuator member. This allows the costs of production of the device to be notably reduced compared to those of the known technique since, unlike those already known, there is only one actuator member associated with the main body and not with the supported element.
The shank preferably comprises an internal cavity open toward the free extremity and equipped with conical inside surface portions with axis coincident to those of the pair of through holes present in the shank and with vertices oriented toward the outside of the shank.
According to one possible embodiment, the two separate parts of the actuator member comprise in their turn spherical external surface portions fit to bear against the conical surface portions present in the cavity of the shank. In this way, it is obtained a particularly optimal spatial distribution of the forces acting on the shank to deform elastically.
According to another possible embodiment of the invention, the two separate parts of the actuator member comprise external conical surface portions fit to bear against the conical surface portions present in the cavity of the shank.
According to a possible embodiment, there are means provided to allow the controlled rotation of the actuator member around its own axis, without extension or contraction, between a first pre-set position, in which the supported element can be inserted into, or removed from, the main body, and at least one second pre-set position in which the shank of the supported element remains locked in the seat and the actuator member can be operated in extension or in contraction.
This advantageously confers particular safety of manipulation of the supported element. In fact, during the disassembly, after having loosened the actuator member, it is necessary to intentionally move the actuator member from the second pre-set position up to the first pre-set position, the only one in which the supported element can be effectively removed from the main body.
According to a further embodiment of the invention, means are provided to allow the controlled rotation of the actuator member around its own axis, without extension or contraction, between the first pre-set position, in which the supported element can be inserted into, or removed from, the main body, at least one second pre-set position in which the shank of the supported element remains locked in the seat and the actuator member con be operated in extension or in contraction, as well as at least one third pre-set position, located between the first and the second pre-set positions, in which the supported element is attached without being locked to the main body without the possibility of extraction from the same.
In this case, the safety of manipulation of the device is further guaranteed since, after loosening the actuator member, further rotation of the actuator member brings it without any effort into a third pre-set position, in which it is not possible, however, to detach the supported element from the main body. To achieve this, it is necessary to apply a further deliberate rotation for a few degrees for the purpose of bringing the actuator member from the third pre-set position up to the first pre-set position, in which the supported element can be removed. Thus, the accidental detachment of the supported element from the main body is prevented.
A further advantageous characteristic of the present invention is given by the fact that the holes of the pair of holes and the corresponding slits of the pair of slits that separate the opposed portions of the shank have different dimensions with respect to each other. Likewise, the two parts of the actuator member comprise substantially cylindrical inserting portions, each having its diameter substantially corresponding to each of the holes and of the slits. This allows the supported element to be always positioned with the same pre-set orientation, thus favouring the repeatability of positioning.
According to another particularly advantageous aspect of the present invention, the supported element comprises a projecting circumferential flange having a spherical surface portion fit to bear against a corresponding spherical surface portion that surrounds the seat of the main body.
The axis of the internal conical surface portions set in the inside cavity of the shank and the axis of rotation of the actuator member when the actuator member is in the first pre-set position, are parallel and reciprocally spaced. Therefore, while the necessary axial force of the shank is exercised in the seat acting on the actuator member, the spherical support surfaces provided on the flange and around the seat of the main body allow precise axial alignment of the supported element with respect to the main body and they also simultaneously provide a particularly wide support surface that prevents the entry of dirt and deposits between the mutually connected parts.
Means are also preferably provided to hold in position a locking device engaged in the driving head of the threaded screw arranged in the actuator member when the actuator member is in the first pre-set position, said means allowing the release of the locking device when the actuator member is in the second pre-set position and in full extension condition. This makes manipulation of the device according to the invention even safer, preventing the accidental separation of the locking device during the operations of connecting or removing the supported element.